As described, for example in JP-A-2006-269348, an optical transmission module used in optical fiber communication has a structure pluggable into an optical transmission apparatus in order to facilitate maintenance and exchange of the module in consequence of breakage and performance degradation.
FIGS. 3A and 3B are views showing an external appearance of a conventional optical transmission module having a pluggable structure. As shown in FIG. 3A, the conventional optical transmission module includes an optical transmission module case 900 made of a metal to accommodate therein a light emitting diode module and a photodetector module, except electrode terminal portions thereof, and a printed wiring board (not shown in FIG. 3A, but denoted by the reference numeral 300 in FIGS. 5A and 5B), and a gasket 800 made of a sheet metal to be mounted on an outer periphery of the case 900.
As shown in FIG. 3B, the gasket 800 is formed at one end thereof with a feather-shaped plate 810, which spreads outside the optical transmission module case 900. Thereby, as shown in FIG. 4, when the optical transmission module is mounted to a metallic cage 700 arranged on a mother board 600 in the optical transmission apparatus, the feather-shaped plate 810 pushes an inner wall of the cage 700 to surely fix the optical transmission module to the cage 700.